Castor



FIG. 1 is a left side and front perspective view of a castor showing ournew design in a front position;

FIG. 2 is a right side elevational view thereof in the same position asthat of FIG. 1;

FIG. 3 is a left side elevational view thereof with the castor in asecond position;

FIGS. 4 and 5 are respective rear and front elevational views thereof;and

FIGS. 6 and 7 are respective top and bottom plan view thereof.

The ornamental design for a castor, as shown and described.